Hydraulic pressure intensifier



June 19, 1962 I J. A. LlND 3,039,271

I HYDRAULIC PRESSURE INTENSIFIER Filed Feb. 25, 1960 2 Sheets-Sheet 1 lNVENTORI \Tolm AL 1nd Mam Ari'or'neys 2 Sheets-Sheet 2 JOHN A. LIN D INVENTOR Y g ATTORNEY June 19, 1962 J. A. LIND HYDRAULIC PRESSURE INTENSIFIER Filed Feb. 25, 1960 w E5 3 m 70 \w m i gm 8 7 m 1 \l M \w 6 v. 6 4 w m 7 w m Q! n? United States Patent 3,039,271 HYDRAULIQ PRESSURE ENTENSIFIER John Alexander Lind, Harpenden, England, assignor to Newton 8: Bennett Limited, a corporation of England Filed Feb. 25, 1960, Ser. No. 10,943 Ciaims priority, application Great Britain Feb. 28, 1959 7 tliaims. (Cl. 66-646) This invention relates to hydro-pneiunatic actuating devices of the kind (hereinafter termed the kind referred to), in which relatively low pneumatic pressure is converted in a pressure intensifier into a relatively higher hydraulic pressure for the purpose of actuating mechanism, such as a hydraulic clamp or the chuck of a machine tool, and having a control valve on the hydraulic side and an actuating lever therefor movable into hold or release positions. Such devices are sometimes termed pressure intensifiers.

One of the problems associated with such devices is the risk of premature release of the hydraulic clamp, chuck or other holding mechanism in the event of failure of the pneumatic supply pressure, as any such pressure failure may cause premature release of the hydraulic clamp or chuck with risk of injury to an operator, or at least, result in some damage to the work and/or to the machine tool.

The object of the present invention is to provide means whereby failure of the pneumatic supply pressure cannot cause premature release of the hydraulic clamp, chuck or other mechanism connected to the hydraulic side pressure intensifier. The mere insertion of a non-return valve to prevent release of hydraulic pressure would not, of itself, be practical because pressure-release means, in addition to the actuating lever for the intensifier, would have to be provided and actuated before the hydraulic clamp, chuck or other hydraulic holding mechanism could be released, and as such, hydraulic holding mechanism is often installed primarily for its speed of actuation and simplicity, any delay or additional operation required of the operative could not be tolerated.

According to the invention, a hydro-pneumatic actuating device of the kind referred to is characterised by a non-return valve incorporated in the hydraulic pressure system in combination with means for neutralising such valve adapted for actuation by movement of the actuating lever of the device into a release position.

In a preferred embodiment of the invention, a nonreturn ball valve is provided in the hydraulic side of the system in combination with pneumatically-actuated release means for unseating the same and connected to the pneumatic control valve for the device so as to be energised when the control lever therefor is moved to the release position.

In the accompanying drawings:

FIG. 1 is a part diagrammatic section elevation of one example of a hydro-pneumatic intensifier constructed in accordance with the present invention;

FIG. 2 is a similar elevation of another example of intensifier.

As shown in FIG. 1, a hydro-pneumatic intensifier consists of a hydraulic cylinder 10 having a piston 11 movable therewithin, under the combined influence of a diaphragm 12 on the one side and a helical compression return spring 13 on the other, a ball valve assembly 14- in the hydraulic system and means whereby said ball valve assembly 14- may be actuated to allow the return passage theret-hrough of hydraulic fluid.

in section, the chamber 10a of the cylinder 10 is of T- shape and the piston 11 occupies the whole of the vertical limb and extends into the head. To the lower end of the piston 11 is attached a curved member 15 whereby the pressure between the diaphragm 12 and the piston 11 "ice may be distributed over a large proportion of said diaphragm. The diaphragm 12 is clamped between the flanges of upper and lower parts 16a, 16b of a diaphragm chamber, the upper member 1601 being rigidly secured to the bottom of the hydraulic cylinder.

The chamber 10a is connected .to the hydraulic feed line 17 by means of a passage 18 extending in an axial direction from the top of the chamber 10a and the ball valve assembly 14. A removable closure plug 19 with washer seals the upper end of passage 18. r

In the upper part of the hydraulic cylinder 10 and at diametrically opposite positions are provided two radially-directed screw-threaded sockets 20 and 21.

A pneumatic cylinder unit 22 is located in the socket 20 and consists of a piston 23 slidably mounted in a chamber 22a and provided with a packing 24 in the normal way. A plunger 25 is secured to piston 23 and extends from said piston through a siutably dimensioned hole bored from the inner face of said socket 2G to the passage 18, sealing packing 22c being provided between the plunger 25 and said suitably dimensioned hole, that portion of the said plunger extending into passage 18 being of smaller diameter than the remainder of the plunger. Said packing 24 abuts face 23a of piston 23, there being a backplate 26 on the other side of the packing 24- which may abut a stop 27. Stop 27 limits the stroke of piston 23 in one direction and is in the form of a cylindrical member of lesser outside diameter than the bore of the chamber and has an annular flange 27a whereby said member may be secured in a corresponding circumferential recess 2% in the wall of the chamber 22a. A return spring 23, placed between face 23b of the piston and the end of the chamber 22a serves to return the piston to its initial position, as shown in the drawings, after displacement therefrom.

A further cylindrical formation 29 is located in screwth'readed hole 21 and includes the ball valve assembly 14. One end of the chamber 29a of the formation 29 is constituted by a plate 3%, secured in a circumferential recess 2% in the wall of the chamber, having centrally positioned therein, a recess Stla. Through the centre of the recess 30a is a hole of a diameter somewhat greater than the diameter of the inner end of plunger 25, in which may be seated a ball 32. Abutting the other side of the ball 32 is a flanged collar 33 having a slightly concave front surface thereto and, between said collar 33 and the other end of the chamber 29a is a return spring 34. The collar 33 is adapted to allow free movement thereby of hydraulic fluid and abutment means are provided as an integral part of the formation 29, whereby the movement of collar 33 may be limited. Said chamber 29:; is connected to the hydraulic feed line 17 by means of a channel 290 through the neck of the cylindrical formation 29, the outer end of the formation being adapted to receive the end of said feed line 17.

Pressure air may be applied to the convex side 12a of the diaphragm 12 from a convenient source, and the same source may provide pneumatic pressure to cylinder unit 22. The source and control means for said pressure air may conveniently be represented by a box 35 having two supply lines 36, 37, an inlet 38 and an exhaust 39. A single movement of control lever 4%} may release the pressure applied to the diaphragm and automatically apply pneumatic pressure to the piston 23 via the pipe 3d, thus moving the plunger 25 to displace the ball 32 from its seating.

Suitable sealing means 41, 42 are provided between the piston 11 and the walls of the lower part of the chamber 10a to prevent loss of hydraulic fluid.

As shown in FIG. 2, the actuating device comprises a cylinder body 5% having mounting lugs 51 at one side.

The lower end of the cylinder is adapted at 52 to receive an air supply pipe. Within the cylinder is a pneumatic piston 53 carrying a self-sealing packing ring 54-. The upper end of the cylinder is closed by a cover 55 in which is a bleed hole 56. The underside of the cover is recessed at 57 to locate the upper end of a conical shaped coil spring 58, the lower end of which is located by a boss 59 on the upper side of the piston 53. Fixed in the said boss 59 is a piston rod 643-, the mounting stern of said rod having an extension 66a adapted to operate as a stop against the end of the cylinder as shown. In the centre of the cover is fixed a gland unit 51 having packing rings 62 and 63.

The cover 55 includes a hydraulic compression chamber 64, coaxial with the piston rod 60 so that such piston rod acts as a displacement member therein. in the upper end of the cover and arranged diametrically transversely thereof, on oppiste sides, are a ball valve unit 65 and a cylinder 66 of a valve actuating unit. T he plug 65 has an axial through hole, the outer end of which at 67 is screw-threaded to receive a hydraulic pipe. The inner end of the plug is recessed and located therein are a spring pad 63, a coil spring 69, a ball pad 7d having peripheral notches '71, a valve ball 72 and a seating 73. Within the cylinder 66 is a pneumatic piston assembly consisting of clamping washers 74 and 74a and a packing ring 75, the outer end of the cylinder is closed by a plug 76 adapted at 77 to receive a coupling for a pneumatic pipe line. The pneumatic piston assembly is mounted on one end of a rod 78, the inner end of which passes through a gland packing 79 in the inner end of the cylinder unit and through a guide hole in the head or upper end of the chamber of the cover 55. The extreme end of the rod 78 is shaped at 78a as a plunger adapted to engage and unseat the ball against the force of its return spring 69. A return spring 70 is provided for the piston assembly.

The device shown in FIG. 2 is substantially the same as shown in FIG. 1 except that the piston 53 and cylinder S replace the diaphragm 12. The device is adapted to be connected to a control valve unit, as shown in FIG. 1, the actuating lever 40 of which, when in the position shown, admits air to the pipe 36 and connects the pipe 37 to the exhaust 39}. W'hen moved to the right to the position shown dotted, the valve unit opens the pipe 36 to the exhaust 39 and admits air pressure to the pipe 37.

In operation, the application of pressure air to the convex side 12a of the diaphragm will cause the piston 11 to move towards and into the upper part of the hydraulic chamber, thus increasing the pressure in the hydraulic system. Movement of hydraulic fiuid past the ball valve is possible during the increase of pressure.

A reduction of air pressure applied to the diaphragm will allow the return of the piston 11, under the influence of return spring 13, with a reduction of hydraulic pressure between the piston 11 and the ball valve. The pressure in the lines between the ball valve and the chuck, hydraulic clamp or similar device is, however, maintained by ball valve 32. If pressure air is applied to the piston 23, the plunger is moved in an axial direction towards the ball 32 and displaces said ball to allow an equalization of pressure through the hydraulic system.

An important feature of the present invention is that a failure of air pressure does not automatically result in the loss of hydraulic pressure in line 17 with a con- 4 sequential reduction of gripping power of a chuck, hydraulic clamp or similar device. Thus, safety of operation is increased.

Although we have described a particular form of the invention, in no Way do we restrict our invention to such details as have hereinbefore been described, since many equivalents will be apparent to one skilled in the art.

I claim:

1. A hydraulic pressure intensifier comprising a hydraulic cylinder having an opening at one end and a compression chamber at the other end, a piston having two ends, one end thereof slidable in said opening and closely fitting the walls thereof, an external chamber attached to said cylinder and into which the other end of said piston extends, a source of pressure connected to said external chamber adapted to actuate the other end of said piston into said compression chamber, spring means in said compression chamber bearing on said piston, a feed line to a device to be hydraulically actuated, a passage from said compression chamber to said feed line, a nonreturn valve in said feed line adapted to be opened by pressure in said passage, a plunger in alignment with said valve, a connection from said pressure source to said plunger, and means for simultaneously releasing pressure from said hydraulic cylinder and applying pressure to said plunger.

2. A hydraulic pressure intensifier according to claim 1 characterized in a diaphragm chamber, a diaphragm mounted therein, said hydraulic cylinder attached to said chamber, said piston in said cylinder attached to the diaphragm to form an assembly, said plunger directed at said valve for unseating the same and pneumatic actuating means for said plunger.

3. A hydraulic pressure intensifier according to claim 1 characterized in that said valve is "a spring pressed ball valve.

4. A hydraulic pressure intensifier according to claim 1 characterized in that said plunger is biased away from said valve in opposition to said applied pressure.

5. A hydnaulic pressure intensifier according to claim 1 characterized in that the means for actuating said plunger is hydraulic pressure.

6. A hydraulic pressure intensifier according to claim 1 characterized in that said piston is attached to a diaphragm and hydraulic pressure against said diaphragm actuates said piston.

7. A hydraulic pressure intensifier according to claim 1 characterized in a piston to which said plunger is attached, a pneumatic cylinder in which said plunger piston operates, a return spring in said pneumatic cylinder and on the underside of its piston, a transversely arranged outlet passage from said hydraulic cylinder communicating with a cylindrical formation, said valve located in said cylindrical formation, said plunger extending into said formation to actuate said valve, a valve seat in said passage and means for holding said valve against its seat in opposition to said plunger.

References Cited in the file of this patent UNITED STATES PATENTS 1,704,817 Ayers Mar. 12, 1929 2,596,348 Tann May 13, 1952 2,618,121 Tucker NOV. 18, 1952 2,646,665 Rockwell July 28, 1953 

